Since the beginning of the nineties, publications on SOI processes are available that can roughly be grouped in two categories: thick-film SOI processes, in which the active silicon layer has a thickness distinctly greater than 1 .mu.m, and thin-film SOI processes, where substantially thinner active silicon layers to below 100 nm are used.
Whereas in thin-film SOI processes the electrical properties of the components differ considerably from standard processes, thick-film SOI processes basically are more suitable therefor.
By insulating circuit portions and/or components on thick-film SOI material, e.g., by using trenches, i.e. vertical insulation layers provided in the depth of the silicon layer for the lateral insulation of functional portions on a chip, considerable advantages over standard technologies may be achieved:
parasitic effects such as latch-up are completely eliminated. PA1 Minorities generated in power switches cannot cause interferences in adjacent circuit portions (e.g. logic circuit portions). PA1 Free components, i.e. components uncoupled from the substrate, such as diodes, offer new possibilities in circuit design.